Transistor ignition system



Feb. 9, 1965 I P. COOK TRANSISTOR IGNITION SYSTEM Filed Aug. 19, 1963 INVENTOR. F275? C o/r fii'TOR VZYJ United States Patent Office 3,168,893 Patented Feb. 9, 1965 3,168,891 TRANSISTOR IGNITION SYSTEM Peter Cook, 763 N. Ehnwood, Wicklilfe, Ohio Filed Aug. 19, 1963, Ser. No. 302,982 7 Claims. (Cl. 123148) This invention relates to improvements in an ignition system especially designed for use in vehicles utilizing an internal combustion engine and more particularly to a novel and improved transistor ignition system.

Heretofore, transistor ignition systems have been designed for use with a specific type of vehicle, and consequently said ignition system has not been adaptable for use with any other type or make of vehicle.

For example, a transistor ignition system heretofore designed for use with one make of a passenger type of automotive vehicle generally has not been adaptable as the ignition system of another manufacturers vehicle.

The transistor ignition system of the present invention however is such that it can be used with almost all, if not all, presently available vehicles manufactured today.

Further, the instant transistor ignition system, as will later be apparent, is more efficient in its operation than transistor ignition systems heretofore used.

Secondly, the transistor ignition system of the present invention may be incorporated into the vehicle as either the primary ignition system or as a secondary ignition system, the primary system in the latter case being the presently known conventional ignition system, so as to afford said vehicle with two separate ignition systems available for alternate use in the event one of said systems becomes inoperative.

In present day conventional ignition systems a pair of breaker points is generally tactuatable by a cam responsive to the engine, said points being connected in series in the primary circuit of the ignition coil, and consequently the current that may flow through said circuit being limited to a value that the breaker points can carry without arcing or more than ordinary deterioration.

In the instant transistor ignition system however, the

primary circuit current of the ignition coil is controlled by a transistor circuit, the engine responsive breaker points being connectable into said transistor circuit and hence operable to control the operation of said transistor circuit wherein the current flowing therethrough may be substantially smaller, and consequently the life of said points is appreciably extended.

It is therefore a primary object of the present invention to provide a transistor ignition system that is readily adaptable for use in a vehicle utilizing an internal combustion engine.

Still another object of the present invention is to provide a novel and improved transistor ignition system which may be combined with the conventional ignition system of an automotive vehicle so as to provide said vehicle with alternatively operable ignition systems.

Another object is to provide a transistor ignition system wherein a transistor circuit controls the current flow between the electrical energy source and the primary winding of the ignition coil of the system.

Still another object of the present invention is the provision of a transistor ignition system which is substantially more rapid in its response to the repetitive opening and closing of the breaker points of the distributor so as to result in a more eflicient ignition cycle than heretofore realized.

Additional objects and advantages of the transistor ignition system of the present invention will be apparent to one skilled in the art to which it pertains and upon reference to the following description of a preferred embodiment thereof and which is illustrated in the accompanying drawings forming a part of this specification and wherein:

FIG. 1 is an electrical wiring diagram shown partially in schematic form of a transistor ignition system embodying the present invention; and,

FIG. 2 is a graphical illustration of the current waveform generated by the transistor ignition system of FIG. 1.

Referring now to the drawings throughout which like elements are designated by the same reference numeral, the transistor ignition system of FIG. 1 is herein shown as it is incorporated into the conventional electrical system of an automobile and combined therein with the conventional ignition system so as to afford said vehicle with two separate ignition systems.

With particular reference directed to FIG. 1 wherein the transistor ignition system is shown in its operative position and the conventional system is shown in its standby position, the numeral 10 designates a source of electrical energy normally provided in the electrical system of an automotive vehicle, such as for example a battery source of power as herein illustrated which may be a 12 volt or 6 volt source of energy, or for larger commercial vehicles, a 32 volt source.

As will be understood, a vehicle ignition system is intended to function so as to provide sufiicient electrical energy to each of the spark plugs of the engine, only one such plug being herein shown at 12, so as to adequately ignite the combustible fuel delivered to the engine cylinders, the ignition system being operable in predetermined timed relationship with respect to said engine so that the fuel is ignited at the proper instant.

The conventional ignition system as herein illustrated includes said battery 10, the positive terminal of which is connectable to cranking motor 25 through relay contact 108 of relay R, the negative terminal of said battery being grounded at G. A suitable ignition switch 15, and ignition coil 17 are connectable to a distributor element 19, and to an engine responsive switch unit 20. Said distributor 19 is connectable, in turn, singularly by conductors 21 with the spark plugs 12 whereby the electrical energy is delivered to the latter.

The ignition switch 15 of the conventional system is controlled by the operator of the vehicle and is operable when turned to its start position to connect the battery 10 through conductor 26, switch contacts 15a, 15c and conductor 28 to one end of the primary winding 17p of the ignition coil 17. Resistance element 30 connected in series with conductor 28 and said primary winding 17p acts to limit current flow in said circuit as will be understood. The opposite end of the primary winding 17p as indicated at terminal Y is connected by a jumper conductor 29 to terminal X of the engine responsive switch unit 20, thereby being connected in parallel with the contacts or breaker points 38 and the condenser 33:: of said switch unit.

One end of magnetizing coil 108a of relay R is connected'by conductor 112 to switch contact 15b, the opposite end of said coil being grounded at G. With the ignition switch turned to start position, the magnetizing coil 108a is connected across the battery 10 and thus energized to close its contact 108 effective to energize the cranking motor 25, effective to crank the engine.

As will be understood, the secondary 17b of the ignition coil 17 of the conventional system is connected through conductor 34 (shown in dotted lines) to the engine responsive rotor element 19a of the distributor which, through said rotor element the electrical energy produced by said ignition coil is directed through each conductor 21 to its respective spark plug 12, said plug being grounded at 36 and being effective thereby to supply the igniting spark for the fuel delivered to its associated cylinder.

Rotor element 20a of the engine responsive switch 20 rotates in response to the operation of the engine to periodically open and close its breaker points 38 which u result in periodically connecting and disconnecting the primary 17p of the distributor coil to and from its aforementioned power source 10.

As is Well known, the operation of the rotor element Et a and the distributor rotor element 19a are synchronized with the engine so as to deliver the energy to the spark plugs at the proper instant effective to ignite the fuel delivered to the engine cylinders.

When the primary winding 17p of coil 17 is disconnected, the magnetic field generated by the same begins to collapse, and as a result thereof an induced EMF. is generated in the secondary 17b which, as a resuit of the turns ratio between said primary and secondary, said induced EMF. is substantially of higher magnitude. This induced E.M.F. is directed through the aforementioned distributor rotor element 19a to each of the spark plugs 13 in proper sequence to thus provide the igniting spark are aforesaid.

As will be noted, the contacts 38 or breaker po nts of switch 26 as oftentimes referred to are serially connected into the primary circuit of the ignition coil 17 and hence determine the permissible fiow of current in said primary circuit.

In the transistor ignition system of the present invention,

as will now be described in detail, the breaker points 38 are connectable into the base circuit of the transistor amplifier whereby less current flows therethrough and the life of said points is substantially extended.

As is also heretofore mentioned, the transistor ignition system is incorporated into the electrical system of the vehicle and combined with the conventional ignition system so that the vehicle is provided with actually two com plete ignition systems which may be alternately used.

With further reference now being directed to FIG. 1, the transistor ignition system of the present invention as is incorporated into the vehicle ignition system includes a transistor amplifier as is indicated in its entirety by the reference numeral 41) being enclosed within dotted lines representing a suitable housing and which amplifier is seen to be a two stage amplifier comprising of transistors 42 and 43, each of which is herein shown as a type pnp transistor. As is known, each of said transistors may also be a npn type with appropriate changes being made in the polarity of the voltages operable therewith and associated changes in circuitry.

The emitter electrode 42c of the transistor 42 is seen to be connected by conductor 45 and serially connected resistor elements 46 and 47, conductor 48, switch contact 49, conductor 149 and fuse element 50 to'the positive terminal P of the battery source 10. The base electrode 42b of said transistor is connectable through conductors 52 and 53 and resistor 60 tothe end of resistor 47 opposite its connection with the aforementioned resistor 46, said base electrode 4212 being thereby in circuit with the positive terminal P of the battery source 10.

The collector electrode 420 of saidtransistor 42 is connected through conductor 63 to the emitter electrode 43e of transistor 43 thereby connecting said transistors in serial cascade.

The collector electrode 43c of transistor 43 is connected through conductor 65 to one end of the primary winding 7 of a suitable ignition coil 72, the opposite end of said primary winding being connected through conductor 73 to the negative terminal of the battery source which side is likewise grounded to the vehicle.

A separate ignition coil 72 is provided with the instant transistor ignition inasmuch as the magnitude'of current generated by amplifier 49 is more than the aforesaid conventional system so as to provide the necessary turns ratio between its primary and secondary windings of at least 1 to 250 and hence the proper magnitude of induced E.M.F. in the secondary for deliverance to the distributor 19.

The base electrode 43b of transistor 43 is connectable through conductor 74 to one end of biasing resistor 75, the opposite end of said resistor connecting to the junction point of resistor 46 and emitter electrode 42e thereby connecting said base electrode 43b in circuit with the positive terminal P of the battery source.

Resistor 76 is seen to have its one end connected to the junction point between conductors 52 and 53 and its opposite end through conductor 73 to the movable switch element 3% of a double pole double-throw toggle switch 31. The base electrode 431) of transistor 43 likewise connects through a unidirectional element such as diode 3! and resistor 81 to said conductor 78.

This transistor ignition system greatly depends for sirnpiicity of installation upon limiting the value of resistors 76 and 81 to a value less than 10 ohms in conjunction with the values of the remaining components hereinafter mentioned to properly function with the conventional ignition equipment such as condenser 33a in the ignition circuit is the ultimate in simplification of installation.

The secondary winding 9% of the ignition coil '72 for the transistor ignition system is seen to have one end con nected to the negative side of the primary coil 7% and its opposite end provided with a terminal T to which the ignition conductor 34 is connected when using the instant transistor ignition.

The transistor amplifier also includes means to contro the energization of transistors 42 and 43 and for this purpose, the magnetizing coil 96 of an electromagnetic contactor $5 is connected at one end by conductor 97 to ground and its opposite end to one end of resistor element 98, the opposite end of the latter connecting to fixed contact 3115 of the toggle switch 31.

A second electromagnetic contactor as identified at 103 is seen to have a normally open contact 164 connected across resistor 46, being thus effective, when closed, to short out said resistor. The magnetizing coil of said contact 193 connects at one end to the vehicle ground, and at its opposite end through conductor 197 to the cranking motor 25 and through normally open contact 108 of magnetic relay R to the positive battery terminal P.

When incorporating the transistor ignition system as just described into the automobile electrical system so that it may be used individually and likewise alternately with the conventional ignition system, the transistor amplifier 40 is preferably housed within a suitable cabinet and mounted within the motor well, the ignition coil 72 likewise being disposed therein so as to be readily available to the distributor 19.

In assembling the amplifier, the aforementioned conductors 149 and 65 are connected respectively to the switch contact 49 and collector 43c of transistor 43 and extend outwardly of the amplifier cabinet.

A conductor 14% is likewise connected to fixed contacts 31a and 31c of toggle switch 31 and extends exteriorly of said amplifier cabinet.

A second conductor 142 connects at one end to movable contact 36a and also extends exteriorly of the aforesaid cabinet.

The conductor 29 previously stated as connected between points X and Y in the conventional ignition system is removed, and conductor 146 is connected to point X and conductor 142 to point Y thus connecting the engine responsive switch 20 and its contacts 38 in series with the toggle switch 3-1 and the primary coil 17p of the ignition coil 17.

Conductor 149 is then connected to one side of the fuse element St and conductor as is connected to the plus terminal of the ignition coil primary 79.

When the transistor ignition system is to be used, the ignition coil conductor 34 is disconnected from the ignition coil 17 and connected to terminal T of the transistor ignition coil '72.

Likewise, the movable contacts Etta, Sill) of toggle switch 31 are shown in contact with fixed switch contacts 31a, 31b, in which position the transistor ignition system is to be used.

To convert over to the conventional ignition system, the coil conductor 34 is connected to coil 17 and toggle switch contacts 30a, 30b are moved into engagement with fixed contacts 31c, 31d, respectively.

Thus, it will now be realized that with the transistor ignition system incorporated with the conventional ignition into the electrical system of the automotive vehicle, as above described, all that needs to be done to convert from the conventional ignition to the transistor ignition or vice versa is to change the ignition coil lead 34 to either coil 17 or 72 and actuate the toggle switch 31 in the proper direction.

Having disclosed the transistor ignition system and the manner in which it is incorporated into the electrical system of an automotive vehicle so as to be utilized as either the primary or secondary ignition system, the manner in which said transistor ignition system functions will now be described.

When the ignition switch 15 is turned to its start position by the operator, switch contacts 15a and 150 are connected to each other an electric current flows from the grounded side of the battery source through coil 96 of relay 95, toggle switch contact 30a, conductor 142, primary winding 17p of coil 17 to ignition contacts'15c, a, and conductor 26 to the positive terminal of said battery source 16.

This flow of current closes contact 49 to thereby connect the battery source 10 to the emitter-base circuit of the amplifier 40 through conductor 48.

As aforementioned, with the ignition key 15 in its starting position, contact 15/7 thereof is also connected to contact 15a to thereby energize coil 108a of relay R so as to close its contact 108 whereby the cranking motor 25 is energized to crank the engine. The coil 105 of contactor 1433 is also connected to the positive terminal P of said battery source through conductor 107 and hence energized.

The contact 104 of contactor 163 is hence closed shorting out resistor 46 during the interval of starting the engine so that maximum current is delivered by the amplifier 40 to the primary 70 of the ignition coil 72.

As the cranking motor turns the engine over, the rotor a of the engine responsive switch 20 likewise rotates to alternately open and close its contacts 38 in the manner as is well known.

When contacts 38 close, the base circuits of the transistors 42, 43 are connected to the system ground thereby providing the base electrodes 42!), 43b of said transistors with the proper bias whereby said transistors immediately become fully conductive.

A substantial amplified current is hence delivered to the primary winding 70 of the ignition coil 72, and generates a large magnetic field around both coils 70 and 90.

As the rotor 20a continues to turn it causes the breaker points 38 to open and at approximately that instant the transistors 42 and 43 are shut off thereby causing a sudden stop of current flow in the primary coil 70.

This sudden stop of current flow causes the primary magnetic field to collapse in the presence of the secondary coil 90 whereby a large voltage is induced in said secondary coil which is then delivered through conductor 34 and distributor 19 to the spark plug 12 connected at that instant to the distributor contact 19a which is thus effective to ignite the fuel delivered to the respective engine cyinder to thus start the engine.

As soon as the engine is started, the ignition switch 15 is moved by the operator to its on position, this usually automatically occurring in the present day type of ignition switch by the operator releasing the key actuator therefor.

When this occurs, contact 15b is disconnected from contact 15a and coil 198a of relay R is de-energized to open its contact 108, and disconnect cranking motor from the battery 10.

Coil 105 of contactor 103 is also de-energized to open its contact 184 and return resistor 46 into the emitter circuit of transistor emitter element 426 which resistor acts as a current limiter in said circuit.

With the engine running, the breaker points 38 are periodically opened and closed being thus effective to provide an ignition pulse to the spark plugs.

FIG. 2 illustrates graphically the pulse waveform de livered by the amplifier to the primary winding '7 0 of the ignition coil.

An important feature in the circuit structure of the present transistor amplifier relates to the base circuitry of each amplifier stage thereof.

As noted in FIG. 1, the base 42b of transistor 42 is connected by conductor 53 and resistor 60 to conductor 48 and the positive terminal P of the battery to thereby provide adequate bias to said base element.

The base 43b of transistor 43 is also seen to connect through conductor 74 and resistor 75 to one side of the switch contact 104 and resistor 46, said elements, as aforesaid, being connected in parallel, and also through resistor 47 and conductor 48 to switch 49 and the positive side of the battery 10.

Thus, it is seen that the bias is separately provided for each base element 42b, 43b of transistors 42, 43.

To complete the base circuit, the base elements 42b, 43b are connected through resistors 76 and 81, respec tively, in parallel with conductor 78, and switch arm 30!) and conductor to the breaker points 38 and hence to ground.

With this circuit structure, when the breaker points 38 are closed, the transistors 42, 43 go into full conduction substantially instantly, the current output thereof rising at a slope rate as is indicated in FIG. 2 at A.

The slope rate indicated in the dotted line at B identifies the time interval utilized by heretofore conventional transistor ignition systems to reach full conduction.

Consequently, in the present transistor amplifier, the bias provided separately to the base element 42!), 43b of each transistor enables the amplifier to reach full conduction within less time as indicated in FIG. 2 by the symbod t than the time required of the heretofore conventional systems as is represented by the symbol t With the amplifier in full conduction, the base voltage of each transistor 42, 43 is somewhat less than the respective emitter voltage. With a 12 volt battery source and the value of circuit components hereinafter referred to as an illustrative embodiment of circuitry, the base voltage of transistar 42 is approximately at 3.25 volts D.C. and the emitter voltage is approximately at 4.5 volts D.C. Likewise, the base voltage of transistor 43 is approximately at 2.8 volts D.C. and the emitter voltage is approximately at 3.8 volts D.C.

When the breaker points 38 open, the potential on each base electrode immediately becomes the same as the battery voltage (12 volts).

Because of the cutoff characteristics of the transistors 42, 43 there still remains at this instant a collector current, and consequently the emitter voltage of each transistor is at a value somewhat less than the source voltage. The voltage of each base electrode therefore reaches the level of said battery potential (12 volts) before its respective emitter electrode reaches this level.

As a result, during the cutoff period for the transistor 42 the base voltage is actually positive with respect to the emitter voltage of electrode 42c which voltage dif ferential is effective to literally drive the transistor 42 to cutoifthe transistor thereby reaching a fully cutoff condition earlier in the cutoff period than has hereto fore been possible to obtain.

Transistor 43 is likewise immediately driven to cutoff inasmuch as the voltage on its base electrode 43b is positive with respect to the voltage on its emitter electrode 43a. The voltage on emitter electrode 43e eventually drops to zero.

The rate of cutoff for the transistor 42 in the present transistor ignition circuitry is identified by the solid line 7 C in FIG. 2, whereas the dotted line D is illustrative of the slower cutoff rate for the heretofore conventional transistor ignition circuitry.

With the transistor amplifier thus driven to cutoff so as to positively cancel the current fiow in the primary winding 70 of ignition coil 72, the resultant collapse of the primary magnetic field immediately genera es a maximum counter in the secondary winding 90 thereof for delivery to the distributor 19 to initiate the spark fire cycle for each spark plug 12.

In one presently available embodiment of transistor ignition system as herein described the following value has been determined for each of the components to give satisfactory operation thereof in a 12 volt electrical ignition system.

Elementi 42, 42 -transistor, pnp, Motorola 2N1555 46, 47 r'esisto'r, .35 ohm, 100 watts 60resistor, ohms, 5 watts 7 5-'-i"'esistor, 1500 ohi'n's, 2 watts 76-resis tor, 7.5 ohms, lwatt's 80-'diode, 2 amps, 400 PIV ill -resistor, 7.5 ohms, watts Having thus described the transistor ignition system of the present invention and illustrated in detail a preferred embodiment thereof as it is incorporated into the electrical system of an automotive vehicle so as to function as either the primary or secondary ignition system for the said vehicle, it will now be apparent that the u same is susceptible to various combinations and arrangements of parts without departing from the inventive concepts thereof as are defined in the claims.

What is claimed is:

1. An ignition system for an internal combustion engine comprising a source of electrical energy, a distributor element connecting to the fuel igniting means for said engine, a primary firing signal generating means, a secondary firing signal generating means, conductor means for selectively connecting one of said generating means to said distributor element, and switch means connected to each of said signal generating means for selectively connecting one of said generating means to said energy source.

2. In an ignition system as is defined in claim 1 and wherein the switch means includes a toggle switch connectable to each pulse generating means.

3. An ignition system for an internal combustion engine comprising a source of electrical energy, a distributor element connecting to the fuel igniting means for said engine, a primary firing signal generating means, a secondary firing signal generating means, conductor means for selectively connecting one of said generating means to said distributor element, first switch means connected to each of said signal generating means for selectively connecting one of said generating means to said energy source, and second switch means responsive to engine operation for rendering the connecting generating means operative.

4. In an ignition system as is defined in claim 3 and wherein the second switch means is connectable between said first switch means and said source.

5 An ignition system for an internal combustion engine comprising a source of electrical energy, a distributor element connected to the fuel igniting means for said engine, a primary firing signal generator means including a first potential transformer connected to said energy source, a secondary firing signal generator means for generating a fuel igniting signal including transistor amplifier means connected to said energy source, a second potential transformer connected to said transistor means, conductor means for selectively connecting said first and second potential transformers to said distributor, first switch means for selectively connecting the primary and secondary signal generator means to said source effective to energize said generator means, second switch means having contact means responsive to engine operation, conductor means for selectively connecting the first potential transformer to said first and second switch means, said second switch means being operable by said engine to periodically close its contact means and provide a pulse of energy to the one potential transformer of said first and second transformer that is connected to said distributor eifective to energize the fuel igniting means.

6. An ignition system as defined in claim 5 and where in the second switch means comprises a double-throw, double-pole switch wherein the primary generator means is connected to said source in one position of said second switch means and the secondary generator means is connected to said source in a second position of said second switch means.

7. An ignition system for an internal combustion engine comprising a direct current source of electrical energy, a distributor element connected to the fuel igniting means for said engine, a primary firing signal generator means including a first potential transformer connected to one side of said energy source, a secondary firing signal generator menas including a first transistor having base, collector and emitter electrodes, a second transistor having base, collector and emitter electrodes, the emitter electrode of said first transistor being connected to the opposite side of said source of energy, the collector electrode of said first transistor being connected to the emitter electrode of said second transistor, a second potential transformer connected to the collector electrode of said second transistor, the base electrode of each transistor being connected to said opposite side of said energy course, first switch means connecting the emitterbase circuit of each transistor to said one end of said energy source to effect the conduction of said transistors and provide a fuel igniting signal therefrom, second switch means for selectively connecting the primary and secondary signal generator means to said one of said source effective to energize the connected one of said generator means, conductor means for selectively connecting the first potential transformer to said first and second switch means, said first switch means being op- .erable by said engine to periodically close its contact means and provide a pulse of energy from the connected potential transformer to said distributor eifective to energize the fuel igniting means.

References Cited by the Examiner UNITED STATES PATENTS 1,964,698 6/34 Walther et al. 123-448 2,412,540 12/46 Sellaro 123148 2,788,780 4/57 Neubauer 123-148 3,072,823 l/63 Kirk 315205 3,087,090 4/ 63 Konopa 315205 RICHARD B. WILKINSGN, Primary Examiner. 

1. AN IGNITION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE COMPRISING A SOURCE OF ELECTRICAL ENERGY, A DISTRIBUTOR ELEMENT CONNECTING TO THE FUEL IGNITING MEANS FOR SAID ENGINE, A PRIMARY FIRING SIGNAL GENERATING MEANS, A SECONDARY FIRING SIGNAL GENERATING MEANS, CONDUCTOR MEANS FOR SELECTIVELY CONNECTING ONE OF SAID GENERATING MEANS TO SAID DISTRIBUTOR ELEMENT, AND SWITCH MEANS CONNECTED TO EACH OF SAID SIGNAL GENERATING MEANS FOR SELECTIVELY CONNECTING ONE OF SAID GENERATING MEANS TO SAID ENERGY SOURCE. 